PICO(1) PICO(1)
NAME
pico - graphics editor
SYNOPSIS
pico [ -mfto ] [ -wN -hN ] [ files ]
DESCRIPTION
Pico is an interactive editor for grey-scale and color
images. Editing operations are expressed in a C-like style.
The options are
-mn Display on a Metheus frame buffer, /dev/omn. A miss-
ing n is taken to be 0.
-f Display on an Itoh frame buffer, /dev/iti0.
-t Show parse trees for expressions; toggled by the
interactive command `tree'.
-o Turn off the optimizer; toggled by `optim'.
Files are referred to in expressions as $n, where n is the
basename or an integer, see f below. Otherwise file names
are given as strings in double quotes, which may be elided
from names that do not contain `/'.
In general, the result of the previous edit operation is
available under the name `old'. The destination of the cur-
rent operation is called `new'.
Pico handles images with coordinates (0,0) in the upper left
hand corner and (X,Y) in the lower right. Brightnesses
range from 0 (black) to Z (white, Z=255). The quantities
X,Y,Z may be used in expressions and set by options:
-w n Set the width X of the work area to n pixels, default
511.
-h n Set the height Y, default 511.
Pico reads commands from the standard input:
help Give a synopsis of commands and functions.
a file
a x y w d file
Attach a new file. Optional parameters x and y give
the origin of a subrectangle in the work buffer; w and
d define width and depth of the image as stored in the
file.
PICO(1) PICO(1)
d file
d $n Delete (close) the file.
h file
Read header information from the file.
r file
Read commands from file as if they were typed on the
terminal. Can not be done recursively.
w file
w - file
Write the file, restricted to the current window (see
below). Use pico format by default. With a minus
flag, write a headerless image (red channel only, if
picture is colored); see also picfile(5).
nocolor
color
Set the number of channels updated in the work buffer
to 1 (black and white) or 3 (red, green, blue).
window x y w d
Restrict the work area to a portion of the work buffer
with the upper left corner at (x,y), and the lower
right at (x+w,y+d).
get file
get $n
The picture file is (re)opened and read into the work
area.
f Show names, sizes, and file numbers of open files.
faster
slower
In slow display the screen is updated once per pixel
computed; in fast display (default), once per line of
pixels.
show name
Show symbol table information, such as the current
value of variables. If name is omitted, the whole sym-
bol table is shown.
functions
Print information on all user defined and builtin func-
tions.
def name ( args ) { program }
Define a function, with optional arguments. Variables
are declared in these styles:
PICO(1) PICO(1)
int var;
global int var;
array var[N];
global array var[N];
x expr
Execute the expression in a default loop over all pix-
els in the current window.
x {program }
Execute the program. The program must define its own
control flow.
q Quit.
EXAMPLES
`pico -w1280 -h1024 -m5'
Get a work buffer that exactly fills a Metheus screen.
a "/tmp/images/rob"
Make a file accessible. It will be known henceforth as
`$rob'.
`a 1280 0 3072 512 junk'
`get $junk'
Direct attention to a 512×512 subrectangle in the mid-
dle of a 3072×512 image stored in a file named junk,
and read it into the workspace.
x new = Z - old
x new[x,y] = Z - old[x,y]
x {for(x=0; x<=X; x++) for(y=0; y<=Y; y++) new[x,y] = Z-old[x,y];}
Three ways to make a negative image. Note the defaults
on control flow and array indexing.
window 0 0 256 256
x new = $1[xclamp(x*2), yclamp(y*2)]
Scale a 512×512 image to one quarter of the screen.
The built-in functions `xclamp' and `yclamp' guard
against indexing out of range.
x { printf("current value of %s[%d]:\t%d\n", "histo", 128, hist[128]); }
Turn off the default control flow (curly braces) and
use the builtin function printf to check the value of
an array element.
SEE ALSO
bcp(1), imscan(1), flicks(9.1), rebecca(9.1), picfile(5),
flickfile(9.5)
G. J. Holzmann, `PICO Tutorial', this manual, Volume 2
G. J. Holzmann, Beyond Photography-the Digital Darkroom,
Prentice-Hall, 1988